Percutaneous technique and implant for expanding the spinal canal

ABSTRACT

The present invention expands a spinal canal by drilling a cylindrical passage in each pedicle of a vertebra, making a circumferential pedicle cut (osteotomy) through each pedicle from within the passage, separating each pedicle cut by inserting an implant into the passage which distracts the pedicle cut to expand the spinal canal, and securing each pedicle cut, allowing the vertebra to heal with the spinal canal expanded. The implant includes an outer sleeve, an inner bolt, and expandable flanges. The outer sleeve includes an upper portion and a lower portion, with the expandable flanges connected to the lower portion and housed within the upper portion. Rotation of the inner bolt causes the upper and lower portions of the outer sleeve to separate, causing the pedicle cut to widen and the expandable flanges to radially extend into and stabilize the widened pedicle cut to effectuate expansion of the spinal canal.

RELATED INVENTIONS

This application is a continuation of U.S. application Ser. No.11/656,790, filed Jan. 22, 2007; which application is a continuation ofU.S. application Ser. No. 10/102,525, filed Mar. 19, 2002 (now U.S. Pat.No. 7,166,107); which application is a continuation-in-part of U.S.application Ser. No. 09/659,180, filed Sep. 11, 2000 (now U.S. Pat. No.6,358,254). The above identified related applications are incorporatedherein by this reference.

FIELD OF THE INVENTION

The present invention relates generally to spinal surgery, and moreparticularly to a method and apparatus for expanding a spinal canal torelieve pressure on spinal nerves.

BACKGROUND OF THE INVENTION

Spinal Stenosis, or narrowing of the spinal canal, inflicts millions ofpeople with back and leg pain due to compression of spinal nerves.Severe spinal stenosis often leads to surgery in an effort to relievecompressed nerves and lessen back and leg pain. Spinal laminectomy isthe traditional operation performed to treat spinal stenosis. In thespinal laminectomy, posterior aspects of the spinal column are removedto “un-roof” the spinal canal to relieve the pressure on the nerves.Specifically, a spinous process, lamina and portions of various facetjoints are the posterior aspects of the spinal column surgicallyexcised.

Although the spinal laminectomy is often successful in relievingpressure on the nerves of the spinal canal, several problems anddisadvantages arise as a result of the laminectomy. First, thelaminectomy removes important sites of back muscle attachment leading toback muscle dysfunction and pain. Second, the laminectomy exposes thenerve sac causing scar tissue to form around the nerves. Scar tissue mayprevent normal motion of the nerves, leading to recurrent pain. Third,the laminectomy can destabilize the spine resulting in a forwardslippage of one vertebra on another. Vertebral slippage can causerecurrent pain and deformity. Fourth, the laminectomy requires a largesurgical exposure and significant blood loss, making the laminectomydangerous for older patients. Finally, spinal stenosis can recurfollowing the laminectomy, requiring risky revision surgery.

Laminectomy risks have led surgeons to seek an alternative for patientswith severe spinal stenosis. Some surgeons choose to treat spinalstenosis with multiple laminotomies. Laminotomies involve removing boneand soft tissue from the posterior aspect of the spine making “windows”into the spinal canal over areas of nerve compression. Multiplelaminotomies remove less tissue than the laminectomy, resulting in lessscaring, vertebral instability and blood loss.

Multiple laminotomies, however, also suffer from problems anddisadvantages. Laminotomies may not adequately relieve nerve compressionand the pain may continue. Laminotomies are more difficult to correctlyperform than the laminectomy. Laminotomies expose the nerves and maycause nerve scaring. Patients receiving multiple laminotomies also oftenhave recurrent spinal stenosis requiring risky revision surgery.

For the foregoing reasons, there is a need for different and bettermethods for relieving the symptoms of spinal stenosis without thedrawbacks of currently available techniques. A method is needed thatexpands the spinal canal, relieving pressure on the spinal nerves, whilebeing simple, safe and permanent.

An initial invention was submitted by the present inventor entitled, “AMethod and Implant for Expanding the Spinal Canal” (now U.S. Pat. No.6,358,254). In the original application, a novel technique was disclosedto expand the spinal canal by lengthening the spinal pedicles on bothsides of a vertebra resulting in decompression of compressed nerveswhile maintaining normal anatomic structures and muscle attachments.This disclosure relies on the same principle, namely that lengtheningspinal pedicles can relieve the symptoms of spinal stenosis. Thisdisclosure achieves expansion of the spinal canal by a percutaneoustechnique, thus eliminating the need for a larger incision.

SUMMARY OF THE INVENTION

The present invention provides a simple, safe, permanent, and minimallyinvasive method and apparatus for treating spinal stenosis by expandingthe spinal canal area to provide additional space for the spinal nerves,relieving pressure on the spinal nerves.

Embodiments of the present invention will be seen variously:

to maintain the integrity of the spinal canal so that the function ofnormal tissues is not destroyed or significantly altered, which canoccur with a laminectomy or laminotomy;

to avoid scarring around spinal nerves by avoiding an open exposure ofthe nerves;

to avoid an alternative procedure that can cause spinal instability,which occurs when one vertebra slips forward on another vertebra causingrecurrent pain and deformity;

to decompress the spinal nerves with a quick, safe approach resulting inminimal blood loss;

to provide a permanent solution to spinal stenosis, where no tendencyexists for recurrence; and to achieve decompression of the spinal canalthrough small percutaneous incisions, rather than a larger incision.

In one aspect of the present invention, a method for correcting spinalstenosis is introduced where a spinal canal is enlarged by cutting avertebra through one or both pedicles, separating the vertebral cut andthen stabilizing the cut. The vertebra can heal with the spinal canalexpanded, thereby permanently creating more space for the spinal nerves,and relieving compression on the nerves.

In another aspect of the present invention, the method of expanding thespinal canal includes drilling a passage or hollow tunnel into at leasta portion of one or both pedicles of a vertebra, making a pedicle cut(osteotomy) from within the passage through to the spinal canal and tothe outside of the vertebra, distracting the osteotomy to expand thespinal canal, and then stabilizing the osteotomy. The osteotomy can bedistracted by longitudinally lengthening the passage in the pedicle(about the cut) from within the passage. In this aspect, distractionoccurs without (and not as a result of) impaction or insertion of astent or implant into the pedicle cut. Or, in other aspects of theinvention, distraction can occur by impaction or insertion of a stent orimplant into the osteotomy.

In another aspect of the present invention, the method of expanding thespinal canal includes the following steps: first, a guide wire isinserted into a central portion of the vertebral pedicles on each sideof a vertebra. This and other method steps can be accomplished with theassistance of x-rays, fluoroscopy, CAT scan or computer assisted imageguidance technology, which are well known in the art of spinal surgery.

Second, the guide wire is used to direct the position of a cannulateddrill (drill with a central barrel or passage to allow introduction overthe guide wire) into each of pedicles to form a passage or hollow tunnelin the central portion of each pedicle. At the conclusion of this stepthe pedicles comprise a hollow column of bone having a central passageand thin, cylindrical, bony walls.

Next, the vertebral pedicles are cut circumferentially, forming an upperportion and a lower portion. A side-cutting instrument can be introducedinto the central passage in each pedicle to perform the circumferentialcut from within the passage. The side-cutting instrument has a cuttingsurface that projects radially outward so that the bony walls of eachpedicle can be circumferentially cut. With both pediclescircumferentially cut, the vertebra is divided into an upper portion(including the spinous process, lamina, transverse process and articularprocesses) and a lower portion (including the vertebral body). Theside-cutting instrument could include a rotating cutting burr orosteotome (chisel) as the cutting surface, both of which are well knownin the art.

Next, each osteotomy (site of the circumferential bone cut) isdistracted (widened or expanded). A specially designed implant can beused to distract the osteotomy by longitudinally lengthening the passagein the pedicle from within the pedicle. In one aspect of the presentinvention, the implant can include an outer sleeve and an inner bolt incommunication with the outer sleeve. Movement of the inner bolt inrelation to the outer sleeve longitudinally lengthens the implant towiden the osteotomy, thereby expanding the spinal canal.

In another aspect of the present invention, the implant can bethreadably inserted into the central passage in each pedicle, and caninclude an outer sleeve divided into an upper and a lower portion; thedivision of the upper and lower portion being positioned at the site ofthe bone cut. The implant could also include an inner bolt capable ofdrawing the upper and lower portions of the outer sleeve apart, eachpart respectively attaching to the upper or lower portion of the pedicleby exterior threads which grip the bony walls of the pedicle.

The lower portion of the outer sleeve could also include expandableflanges which expand by the action of the inner bolt of the implant,resulting in the flanges being positioned between the drawn apart edgesof the cut pedicle. The inner bolt of the implant could ultimately spanacross the separation between and engage the upper and lower portions ofthe outer sleeve, allowing secure fixation of the upper and lowerportions of the outer sleeve by the action of the inner bolt.

Finally, the pedicle cut is secured in the elongated position, which canbe accomplished by the action of the expandable flanges interposedbetween the cut surfaces of the pedicle and the inner bolt, the innerbolt securing the upper and lower portions of the outer sleeve bycrossing the junction between the upper and lower portions of the outersleeve.

The drawing apart of the upper and lower portions of the pedicles oneach side of the pedicle cut cause expansion of the spinal canal,achieving pressure relief on the spinal nerves. The implants remains inthe elongated pedicles, allowing bony healing of the pedicles, and thuscreating permanent expansion of the spinal canal and preventingrecurrence of the spinal stenosis.

In another aspect of the present invention, the expandable flangesinclude osteogenic material to assist in the healing of the osteotomysite, allowing the pedicles to heal in the elongated position, therebypermanently expanding the spinal canal.

In another aspect of the current invention, the implant includes acentral barrel allowing introduction of the implant over a guide wire.

The present invention differs from current, unrelated techniques fortreating spinal stenosis for at least the following reasons:

(1) Normal spine structures are not removed and thus normal muscleattachments are maintained;

(2) There is less chance of spinal instability;

(3) There is less manipulation of the spinal nerves;

(4) There is less scaring around the spinal nerves;

(5) Spinal decompression is more complete;

(6) The operation is quicker and safer with less blood loss;

(7) The expanded spinal canal is permanent, preventing recurrent spinalstenosis; and

(8) The procedure can be accomplished in a percutaneous fashion throughvery small incisions.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings a form which is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 illustrates a cross-section of a vertebra with a guide wirepassing through a central region of a pedicle;

FIG. 2 illustrates the cross-section of the vertebra of FIG. 1, with acannulated drill passing over the guide wire and drilling a passage intothe central region of the pedicle;

FIG. 3 illustrates the cross-section of the vertebra of FIG. 1, showinga passage (hollow tunnel) in the central region of the pedicle followingthe cannulated drilling of FIG. 2;

FIG. 4 illustrates the cross-section of the vertebra of FIG. 1, with aside-cutting instrument in the passage in the pedicle performing a cutthrough an outer bony wall of the pedicle;

FIG. 5 illustrates an enlarged view of FIG. 4, showing a cutting surfaceof the side-cutting instrument penetrating through the outer bony wallof the pedicle;

FIG. 6 illustrates the cross-section of the vertebra of FIG. 1, with thecutting surface of the side-cutting instrument completing a cut throughan inner bony wall of the pedicle to the spinal canal;

FIG. 7 illustrates an enlarged view of FIG. 6, showing the cuttingsurface of the side-cutting instrument penetrating through the innerbony wall of the pedicle to the spinal canal;

FIG. 8 illustrates the cross-section of the vertebra of FIG. 1, with acompleted circumferential cut through the pedicle, separating thepedicle into upper and lower portions;

FIG. 9 illustrates the cross-section of the vertebra of FIG. 1, withcompleted circumferential cuts through both pedicles, separating thevertebra into upper and lower portions;

FIG. 10 illustrates a cross-section of an implant used to elongate andstabilize the pedicles, the implant shown in a pre-elongating position;

FIG. 11 illustrates a cross-section of the implant of FIG. 10 in apedicle elongating position;

FIG. 12 illustrates the cross-section of the vertebra of FIG. 1, withthe implant inserted into the passage of each pedicle, the implantinserted in the left pedicle shown in the pre-elongating position andthe implant inserted in the right pedicle shown in the pedicleelongating position;

FIG. 13 illustrates an enlarged view of the left pedicle of FIG. 12,showing the implant inserted in the passage in the pre-elongatingposition and aligned in the passage to begin pedicle elongation;

FIG. 14 illustrates an enlarged view of the right pedicle of FIG. 12,showing the implant inserted in the passage in a pedicle elongatingposition, with expandable flanges of the implant filling and securing awidened circumferential cut in the pedicle after pedicle elongation.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, where like numeral indicate likeelements, there is shown in FIG. 1 a cross section of a vertebra 1having a vertebral body 5, spinal canal 3 and pedicles 2. Also shown isa guide wire 4 inserted into a central portion of the left pedicle 2 toenter the vertebral body 5.

FIG. 2 illustrates the cross section of the vertebra 1 of FIG. 1,showing a cannulated drill 6 passing over the guide wire 4, drilling apassage in the central portion of the left pedicle 2 but leaving intactouter wall 23 of the left pedicle 2.

FIG. 3 illustrates the cross section of the vertebra 1 of FIG. 1following completion of the drilling procedure of FIG. 2, showing apassage 7, or hollow tunnel, spanning the central portion of the leftpedicle 2, leaving intact an outer bony wall 23 of the left pedicle 2.

FIG. 4 illustrates the cross section of the vertebra 1 of FIG. 1 with aside-cutting instrument 8 within the passage 7 of the left pedicle 2.The side-cutting instrument 8 has an opening 9 which allows a cuttingsurface 10 to pass radially outward from a longitudinal center of theside-cutting instrument 8. The cutting surface 10 is seen penetratingthe outer bony wall 23 of the left pedicle 2.

FIG. 5 illustrates an enlarged view of the cross section of the vertebra1 of FIG. 1, showing the side-cutting instrument 8 within the passage 7of the left pedicle 2. The cutting surface 10 is passing radiallyoutward from the side-cutting instrument 8 and penetrating the outerwall 23 of the left pedicle 2. The cutting surface 10 of theside-cutting instrument 8 is capable of extending and withdrawing insuch a way that it can penetrate through the bony wall 23 of the leftpedicle 2. By extending and withdrawing the cutting surface 10, andturning the side-cutting instrument 8 within the passage 7, exposing theopening 9 and the cutting surface 10 to pedicle wall material, theside-cutting instrument 8 can create a circumferential cut (anosteotomy) through the left pedicle 2, separating the left pedicle intotwo portions, an upper portion and a lower portion.

FIG. 6 illustrates a cross-section of the vertebra 1 of FIG. 1 with thecutting surface 10 of the side-cutting instrument 8 extended andpenetrating an inner wall 24 (along the spinal canal 3) of the leftpedicle 2, creating a cut through to the spinal canal 3.

FIG. 7 illustrates an enlarged view of the cross section of the vertebra1 of FIG. 1, showing the side-cutting instrument 8 within the passage 7of the left pedicle 2. The cutting surface 10 is passing radiallyoutward from the side-cutting instrument 8, penetrating the inner bonywall 24 of the left pedicle 2 through to the spinal canal 3.

FIG. 8 illustrates a cross section of the vertebra 1 of FIG. 1 with acompleted circumferential cut (an osteotomy) 11 through the left pedicle2, separating the left pedicle 2 into an upper portion 12 and a lowerportion 13.

FIG. 9 illustrates a cross section of the vertebra 1 of FIG. 1, withpassages 7 drilled in both the left and right pedicles 2 andcircumferential cuts 11 in the midportions of both pedicles 2. Thecircumferential cuts 11 divide the pedicles 2 into upper portions 12 andlower portions 13 in such a way that upper portion 14 and lower portion15 of the vertebra 1 are completely detached.

FIG. 10 illustrates a cross section of an implant 16 used to elongatethe pedicles 2, thereby widening the circumferential cut 11 andexpanding the spinal canal 3. The implant 16 also secures the pedicles 2in an elongated position. The implant 16 is shown in a pre-elongatingposition.

The implant 16 includes an outer sleeve 17 and an inner bolt 18. Theouter sleeve 17 is both externally and internally threaded. The innerbolt 18 is externally threaded to engage the internal threads of theouter sleeve 17. The outer sleeve 17 is divided into an upper portion 19and a lower portion 20. The upper portion 19 and lower portion 20 of theouter sleeve 17 are divided at a separation point 25.

The lower portion 20 contains expandable flanges 21 which fit into theupper portion 19 of the outer sleeve 17 (as shown in FIG. 10) when theimplant 16 is in a pre-elongating position. The inner bolt 18 includes acentral barrel 22, allowing pass-through of a guide wire 4 (shown inFIG. 10) to assist in correctly aligning the implant 16 within thepassage 7 in the pedicle 2. In the pre-elongating position, the innerbolt 18 of the implant 16 is partially housed within the outer sleeve17. A distal end 26 of the inner bolt 18 contacts the expandable flanges21 of the lower portion 20 of the outer sleeve 17. The distal end 26 ofthe inner bolt 18 is designed to not only contact the expandableflanges, but also to wedge itself under a reveal 27 formed due to theflared design of an upper tip of the expandable flanges 21.

FIG. 11 illustrates the implant 16 of FIG. 10 in a pedicle elongatingposition. The inner bolt 18 is fully inserted into the outer sleeve 17.By fully and threadably inserting the inner bolt 18 into the outersleeve 17, the lower portion 20 of the outer sleeve 17 moves away fromthe upper portion 19 of the outer sleeve 17, at separation point 25,causing overall elongation of the outer sleeve 17. The expandableflanges 21 of the lower portion 20 of the outer sleeve 17 are opened(expanded) to extend beyond the outer diameter of the outer sleeve 17.In the pedicle elongating position, the expandable flanges 21 lie withinthe separation between the upper 19 and lower 20 portions of the outersleeve 17. The upper 19 and lower 20 portions of the outer sleeve 17 aresecured in the elongated position by the inner bolt 18, which isthreaded across the junction (separation) between the upper 19 and lower20 portions of the outer sleeve 17, securing the upper 19 and lower 20portions in the pedicle elongating position.

FIG. 12 illustrates a cross section of the vertebra 1 of FIG. 1, showingthe implant 16 inserted into the right and left pedicles 2. The rightpedicle 2 includes an implant 16 in a pedicle elongating position, whilethe left pedicle 2 includes an implant in a pre-elongating position.Note that FIG. 12 shows the right pedicle 2 elongated and the leftpedicle in a pre-elongating state. The right, elongated pedicle 2 causesan asymmetrical tilt to the upper portion 14 of the vertebra 1 in theFIG. 12 view, which is balanced upon elongation of the right pedicle 2.Also note the alignment of the separation point 25, in relation to thecircumferential cut 11, of the pre-elongated implant 16 in the leftpedicle 2.

FIG. 13 illustrates an enlarged view of the vertebra 1 of FIG. 1,showing the implant 16 of FIG. 12 inserted into the left pedicle 2 in apre-elongating position. The implant 16 is inserted over the guide wire4 to ensure correct alignment of the implant 16 within the passage 7. Inthe pre-elongating position, the expandable flanges 21 are housed withinthe upper portion 19 of the outer sleeve 17. The distal end 26 of theinner bolt 18 contacts the upper tip of the expandable flanges 21. Theseparation point 25 is positioned adjacent to an upper edge 28 of thecircumferential cut (osteotomy) 11.

FIG. 14 illustrates an enlarged view of the vertebra 1 of FIG. 1,showing the implant 16 of FIG. 12 inserted into the right pedicle 2 in apedicle elongating position. The inner bolt 18 has been threadablyinserted completely into the outer sleeve 17, causing the upper portion19 and the lower portion 20 of the outer sleeve 17 to separate, furthercausing the expandable flanges 21 to open, extending beyond the confinesof the outer sleeve 17 and into the circumferential cut 11 of thepedicle 2. The expandable flanges 21, projecting into thecircumferential cut 11, prevents the upper portion 12 and the lowerportion 13 of the pedicle 2 from moving (shortening) back to theiroriginal, non-elongated position.

In operation, one method for expanding the spinal canal is summarized asfollows: first, the guide wire 4 is placed into the central portion ofthe pedicle 2 of the vertebra 1 (FIG. 1). Assistance with the entireprocedure (operation) could be obtained through fluoroscopy, x-ray, CATscan or computerized image guided technology, which are all well knownin the art of spinal surgery.

Next, the guide wire 4 is over drilled with a cannulated drill 6,leaving a passage (hollow tunnel) 7 through the central portion of thepedicle 2 but leaving the outer walls 23 intact (FIG. 2). The cannulateddrill 6 is then withdrawn, leaving the guide wire 4 in place (FIG. 3).

Next, a circumferential cut (osteotomy) 11 is placed in the pedicle 2(FIGS. 4-7), using a side-cutting instrument 8 inserted into the passage7 in the pedicle 2. The side-cutting instrument 8 includes a cuttingsurface 10, which is extended and withdrawn from a side opening 9 in theside-cutting instrument 8. By extending the cutting surface 10 throughthe side opening 9 in the side-cutting instrument 8 and turning theside-cutting instrument 8 within the passage 7 of the pedicle 2, theentire pedicle 2 is divided in a circumferential fashion, creating thecircumferential cut (osteotomy) 11 (FIG. 8). With both pedicles 2 cut,the upper portion 14 and the lower portion 15 of the vertebra 1 areseparated, with no bony material left holding the upper 14 and lower 15portions together (FIG. 9).

Next, the pedicles 2 are elongated at the site of the circumferentialcut 11 using the implant 16 (FIGS. 10-14). The implant 16, in apre-elongating state, is first threadably inserted into the pedicle 2using the guide wire 4 to assist the implant 16 into the correctposition (left pedicle 2 of FIG. 12). Following insertion of the implant16, the guide wire 4 is removed.

The pre-elongated extended implant 16 is positioned within the passage 7of the pedicle 2 to align the upper edge 28 of the circumferential cut11 with the demarcation (separation) point 25 between the upper 19 andthe lower 20 portions of the outer sleeve 17 (FIG. 13). This precisealignment is not critical, however, as placement of the separation point25 of the outer sleeve 17 within the boundaries of the circumferentialcut 11 is sufficient.

The inner bolt 18 of the implant 16 is then threaded into the outersleeve 17 causing the upper 19 and the lower 20 portions of the outersleeve 17 to move apart. Because the exterior threads of the upper 19and the lower 20 portions of the outer sleeve 17 have a good mechanicalpurchase of the bone of the upper 12 and the lower 13 portions of thepedicle 2, the pedicle is elongated a few millimeters (by a widening ofthe circumferential cut 11) as the upper 19 and the lower 20 portions ofthe outer sleeve 17 are drawn apart. The upper portion 19 of the outersleeve 17 may need to be held motionless to assure that the upper 19 andthe lower 20 portions of the outer sleeve 17 begin moving apart.

During rotation of the inner bolt 18, the distal end 26 of the innerbolt 18 pushes against the upper tip of the expandable flanges 21,causing the upper 19 and the lower portions 20 of the outer sleeve 17 toseparate until the expandable flanges 21 clear the lower edge of theupper portion 19 of the outer sleeve 17. When the expandable flanges 21are no longer contained within the upper portion 19 of the outer sleeve17, the distal end 26 of the inner bolt 18 wedges itself under thereveal 27 (FIGS. 10-11) formed by the upper tip of the expandableflanges 21, pushing the expandable flanges 21 radially outward due tothe force exerted by the inner bolt 18. The radial expansion of theexpandable flanges 21 allows the inner bolt 18 to travel behind theradially extended expandable flanges 21 and threadably engage theinternal threads of the lower portion 20 of the outer sleeve 17 (FIG.14). The inner bolt is now threadably attached to the upper 19 and thelower 20 portions of the outer sleeve 17, thereby mechanically holdingthe expandable flanges 21 in an open, radially extended position withinthe circumferential cut 11, locking the upper 19 and the lower 20portions of the outer sleeve 17 together, and securing the pedicle 2 inan elongated position (with widened circumferential cut 11) to providean expanded spinal canal (FIG. 14).

An identical procedure is followed for the pedicles of both the rightand the left side of the vertebra 1. To assist with pedicle healing atthe circumferential cut 11, the expandable flanges 21 could be made of,or include, an osteogenic material to promote bone healing across thesite of the pedicle 2 elongation.

These and other advantages of the present invention will be apparent tothose skilled in the art from the foregoing specification. Accordingly,it will be recognized by those skilled in the art that changes ormodifications may be made to the above-described embodiments withoutdeparting from the broad inventive concepts of the invention. It shouldtherefore be understood that this invention is not limited to theparticular embodiments described herein, but is intended to include allchanges and modifications that are within the scope and spirit of theinvention.

1. A method for expanding a spinal canal, comprising the steps of: drilling at least one passage into a vertebra; performing a vertebral cut from within each passage through to the spinal canal and through to an outside of the vertebra; and widening each vertebral cut, by longitudinally lengthening the at least one passage from within the at least one passage, to enlarge the spinal canal.
 2. The method of claim 1, wherein the vertebra is cut through the pedicle, and widening each vertebral cut elongates the pedicle, thereby enlarging the spinal canal.
 3. The method of claim 1, further comprising a preliminary step of introducing a guide wire into the vertebra to guide the drilling of the at least one passage into the vertebra.
 4. The method of claim 3, wherein a cannulated drill is positioned over the guide wire to drill the at least one passage into the vertebra.
 5. The method of claim 1, wherein the at least one passage in the vertebra is located in the pedicle of the vertebra, the passage forming a hollow, cylindrical column within the pedicle.
 6. The method of claim 1, wherein the vertebra is cut circumferentially from within the passage using a side-cutting instrument.
 7. The method of claim 6, wherein the side cutting instrument includes a cutting surface that projects radially outward and is rotatably movable to perform the circumferential vertebral cut.
 8. The method of claim 1, wherein an implant is inserted into the passage, and upon operation of the implant, lengthens the passage along a longitudinal length of the passage, to widen the vertebral cut to expand the spinal canal.
 9. The method of claim 8, wherein the implant includes external threads and is threadably introduced into the passage, the external threads of the implant engaging walls of the passage on either side of the vertebral cut.
 10. The method of claim 8, wherein the implant includes an outer sleeve and an inner bolt in communication with the outer sleeve, wherein movement of the inner bolt in relation to the outer sleeve longitudinally lengthens the passage to widen the vertebral cut to expand the spinal canal.
 11. The method of claim 10, wherein the outer sleeve of the implant includes an upper portion and a lower portion, wherein movement of the inner bolt in relation to the outer sleeve separates the upper portion from the lower portion, thereby widening the vertebral cut.
 12. The method of claim 11, wherein the implant further includes expandable flanges, wherein the flanges extend radially outward from the implant upon separation of the upper portion from the lower portion and are positioned within the vertebral cut to stabilize the vertebral cut.
 13. The method of claim 12, wherein the inner bolt secures the upper portion to the lower portion, about the expandable flanges, to maintain the widened vertebral cut.
 14. The method of claim 12, wherein the expandable flanges are movably attached to the outer sleeve, wherein movement of the inner bolt causes a distal end of the inner bolt to bear against a respective tip of each expandable flange to radially extend each expandable flange outward beyond an exterior of the outer sleeve and into the vertebral cut, thereby stabilizing the vertebral cut.
 15. The method of claim 11, wherein the inner bolt, after threadably engaging an inner channel of the upper portion, communicates in a bearing relationship with the lower portion, to translate the upper portion away from the lower portion about the vertebral cut to widen the vertebral cut.
 16. The method of claim 11, wherein movement of the inner bolt separates the upper portion from the lower portion to widen the vertebral cut by abutment of the inner bolt against the lower portion.
 17. The method of claim 11, wherein the upper portion is mechanically secured to the lower portion after widening the vertebral cut to maintain the widened vertebral cut.
 18. A method for expanding a spinal canal, comprising the steps of: drilling at least one passage into a vertebra, forming a hollow, cylindrical column extending into at least a portion of a pedicle of the vertebra; inserting a side cutting instrument into each passage and making a pedicle cut from within the passage through to the spinal canal and through to an outside of the vertebra; inserting an implant into each passage, the implant engaging walls of the passage on either side of the pedicle cut, and operating the implant from within the passage to distract the pedicle cut and expand the spinal canal.
 19. The method of claim 18, wherein operating the implant includes turning an inner bolt about its longitudinal axis, the turning inner bolt communicating with the upper and lower portions of the implant to separate the lower portion from the upper portion, the separation of the lower portion from the upper portion serving to distract the pedicle cut, and wherein the implant further includes expandable flanges that extend radially outward from the implant, upon separation of the upper portion from the lower portion, and extend into the vertebral cut to stabilize the vertebral cut.
 20. The method of claim 19, wherein the inner bolt secures the upper portion to the lower portion, about the expandable flanges, after extension of the expandable flanges into the vertebral cut, to maintain the widened vertebral cut. 